Introducer sheaths are commonly used in various medical procedures where a catheter is transcutaneously introduced into an interior body lumen or cavity, such as a blood vessel or a hollow body organ. Typically, the introducer sheath comprises a thin-walled sheath tube that is introduced through a previously formed needle penetration. The introducer sheath can be introduced together with an internal stylet or obturator, where the stylet or obturator has a tapered distal end that extends from the sheath and dilates the previously formed hole as the sheath is advanced. After the combination of the sheath and stylet/obturator has been introduced, the stylet/obturator is removed, leaving a working access lumen defined by the sheath. Catheters and other working devices can then be introduced through the access lumen to perform various medical procedures.
It may be desirable to remove the sheath and leave the catheter resident in the artery or vein. Unfortunately, conventional sheaths have a drawback in that typically they cannot be withdrawn after insertion of a catheter or other device. Most catheters terminate at enlarged hubs which prevent conventional sheaths from sliding off over the end. The sheath, therefore, must remain resident in the vein or artery throughout the procedure.
A known solution is a peel-away or splittable sheath. Generally, peelable sheaths permit removal of the sheath after insertion because it is not necessary for them to pass over the hub of the catheter. Peelable sheaths provide advantages over prior sheaths. The sheath must be constructed of a smooth biocompatible material with a low coefficient of friction. These materials are typically chemical resistant. However, known peelable sheaths also have drawbacks. Peelable sheaths are more flexible than their predecessors and, thus, are not as responsive to manipulation, e.g., during insertion. This is particularly true for peelable sheaths having tabs preformed by open ended slits, because once the tabs are formed, the sheath loses much of its structural integrity.
The material of the sheath also presents a challenge to its manufacturers. The sheath must be constructed of a smooth biocompatible material with a low coefficient of friction. These materials are typically chemical resistant. More importantly, when the sheath is a peelable sheath, the material must be easily splitable but still retain some structural rigidity. Additionally, because the sheath material must have the above qualities, adhering a fitting to the sheath can be difficult.